Method and apparatus for manufacturing pipettes



14, 1967 c. A PORTER ETAL 3,309,188

METHOD AND APPARATUS FOR MANUFACTURING PIPETTES Filed Sept. 5, 1 963 3Sheets-Sheet l INVENTORS CHARLES APORTER WILBUR A.SCHRE(NER A'IT RNEVS1967 c. A. PORTER ETAL 3,309,18

METHOD AND APPARATUS FOR MANUFACTURING PIPETTES Filed Sept. 5, 1963 3SheetsSheet 2 F i G u 2 INVENTOR5 CHARLES A. PORTER BY LON-BUR ASCHP-EINER ATTO RN EVS Max-ch14, 196? c. A. PORTER ETAL METHOD ANDAPPARATUS FOR MANUFACTURING PIPETTES 3 Sheets-Sheet 5 Filed Sept. 3,1963 INVENTORS CHARLES A. PORTER wLBuR A. SCHREINER A'ITORNEVS UnitedStates Patent Filed Sept. 3, 1963, Ser. No. 306,024 6 Claims. (Cl.65-109) This invention relates to a method and apparatus for formingconstant volume bulbs of pipettes and similar items of glassware fromtubular blanks.

More particularly, this invention relates to a method and apparatus forforming pipettes from tubing blanks by heating a portion of the blankand expanding the heated and softened portion thereof against preciselylocated, complementary rotating dies which are moved into closeproximity to the heated portion of the tubing.

It has been the practice in the past to form the bulb portion of apipette from two separate pieces of glass having enlarged ends which arethen joined together. Such a procedure is set forth in US. Patent No.2,735,230 of V. Morrill, Jr., dated Feb. 21, 1956. One problemencountered in the making of pipettes is the calibration of the pipetteand frequently it is necessary that each pipette be calibratedindividually. This is due to the fact that in present processes forforming pipettes there is no assurance that each pipette will have thesame precise internal volume configuration throughout the length of thepipette. It can readily be appreciated that the calibration of pipetteson an individual basis is a time consuming and thus a costly step in theproduction of precision calibrated pipettes.

With the foregoing in view, it is an object of this invention to providea method of forming pipettes with bulb portions from a length of tubingin which the internal volume of the pipette is made with precision andaccuracy.

It is an additional object of this invention to provide a method ofmaking successive pipettes in which all of the pipettes have the sameprecise volume.

It is a further object of this invention to provide apparatus forforming pipettes in which thevolume of the pipettes is made withprecision.

It is a still further object of this invention to provide apparatus forexpanding a portion of a heated tubing against precisely positionedroller dies so that the volume of successively produced pipettes is thesame.

Other and further objects will be apparent from the followingdescription taken in conjunction with the annexed sheets of drawings,wherein:

FIG. 1 is a perspective view of the apparatus of the invention;

FIG. 2 is a perspective View of a portion of the apparatus illustratedin FIG. 1, on an enlarged scale, showing the initial step of heating atubular blank;

FIG. 3 is a perspective view, similar to FIG. 2, illustrating theposition of the roller dies when in forming position during theexpansion of the bulb portion of the pipette into the area between thedies;

FIG. 4 is a partial, sectional view taken at line 44 of FIG. 2; and

FIG. 5 is a plan view of the roller dies and tubing 3,309,188 PatentedMar. 14, 1967 blank illustrating the relationship therebetween duringthe forming of the bulb portion of a pipette.

With particular reference to the drawings, the appara tus of theinvention takes the form of a lathe having a base or bed 10 which servesto support a pair of parallel, horizontal bed rails 11 and 12 in fixedposition spaced above the base of the lathe. The left hand end of thelathe, as shown in FIG. 1, carries a fixed head stock 13 and the bedrails 11 and 12 support a tail stock 14 for adjustable movement towardand away from the head stook. Both the head stock and tail stock carryhorizontally extending co-axial shafts 15 and 16 in opposingrelationship with the shafts carrying chucks 17 and 18 respectively attheir extending ends. The shaft 15 has a spur gear 19 fixed theretowhich is in mesh with a drive gear 20. The drive gear 20 is mounted on asplined shaft 21 which extends into a complementary spline opening inthe drive shaft 22 of a motor 23. The motor 23 is mounted on themoveable tail stock 14 and its drive shaft 22 also carries a drive gear24 which is in mesh with a spur gear 25 carried by the shaft 16 fordriving the chuck 18. The splined connection between the two shafts 2'1and 22 is necessary from the standpoint that the tail stock is moveablerelative to the head stock for holding glass tubing or blanks of varyinglengths in proper position in the chucks 17 and 18.

It should be pointed out that the chuck 18 and its shaft 16 is providedwith an axial opening 26 therethrough to provide access for air underpressure being fed thereto through a flexible line 27. The line 27 isconnected to the shaft 16 by a rotary connector 28 so that the shaft 16may rotate while the flexible line 27 remains stationary. The chucks 17and 18 are of the type having three spring biased jaws 29 3 1. Each ofthe jaws is biased in a counterclockwise direction, as viewed in FIGS.1-3. With the placing of the tubing T in position between the jaws, itcan readily be seen that the sides of the jaws 29-3-1 contact the sideof the tubing at three equal, circumferentially spaced points on thetubing and effectively grip the tubing and center it with respect to thechuck body-18. In this manner both ends of the tubing T are supported bythe chucks 17 and 18 and held in precise horizontal position. Thedetails of the chucks are not important to the invention except to theextent that they provide an arrangement for supporting a length oftubing and for rotating the tubing about its longitudinal axis, withboth chucks being rotated at the same speed. The chuck 1 8, aspreviously described, has an opening 26 therethrough and within theinner end of this opening 26, is fixed an annular sleeve 32.

The sleeve 32 carries within its bore a bushing 33 which extends throughthe bore to a point less than the full length of the sleeve 3'2. Thesleeve, at its forward end, has an enlarged annular recess 34 and theend of the bushing 33 extends to a point within this recess 34. Theextending end of the bushing 33 is provided with elongated slots 35which extend through the wall thereof and provides communication betweenthe bore of the bushing 33 and the annular recess 34 of the sleeve 32.The end of the bushing 33 serves as the locating surface against whichthe tubing T is seated and, in effect, defines the position of themoveable chuck 1-8 with respect to the tubing T.

It can readily be seen that the introduction of air under pressurewithin the opening 26 in the chuck 18 will convey air under pressurethrough the bushing 33 and into the open end of the tubing T, with thevolume of air being diminished to a certain extent by the escape of airthrough the slots 35 of the bushing. The slots 35 also serve as airbleed openings to prevent development of excessive pressure within thetubing T.

It should be understood that the air under pressure which is blown intothe open end of the tubing T is supplied in a predetermined cycle, aswill be explained later with respect to the operation of the apparatus.

It should also be understood that the chuck 17 has jaws similar to thoseshown with respect to the chuck 18. However, the chuck 17 is notsupplied with air under pressure and the tubing T used to form thepipettes actually has a tapered, restricted end and it is this taperedend which is gripped by the jaws of the chuck 17. This end of the blankis left open with the restriction therein being suflicient to provide aback pressure in the blank to expand same.

Intermediate the length of the rails 11 and 12 there is providedsleeve-like members 36 and 37 which are adapted to slide on the rails 11and 12. The sleeve-like members 36 and 37 support a relatively flatplatform 38. The platform 38 spans the distance between the two rails 11and 12 and serves as the mounting base for a pair of roller dies 39 and40.

As best shown in FIGS. 1 and 3, the platform 38 is formed with twovertically extending portions 41 and 42 which extend vertically to thesame extent with upper ends thereof being below the span of the tubingT. The portions 41 and 42 serve as end supports for a pair ofhorizontally extending shafts 43 and 44. Both shafts 43 and 44 extendthrough the portion 41 and carry a pair of sprockets 45 and 46 fixedthereto. In addition to the sprockets 45 and 46, the shaft 44 has athird sprocket 47 fixed thereto which serves as the drive sprocket.

The shaft 44, intermediate the vertical portions 41 and 42, carries apair of spaced sleeve bearings 48 and 49. Both the sleeve bearings 48and 49 have vertically extending arms 50 and 51 connected theretorespectively and to the upper ends of these arms are fixed sleevebearings 52 and 53. A horizontal shaft 54 is supported in the sleevebearing 52 at one end thereof and extends through the sleeve bearing 53.Intermediate the two sleeve bearings 52 and 53 the shaft 54 carries theroller die 40. The extending end of the shaft 54 carries, or has fixedthereto, a sprocket 55. In a similar manner the shaft 43 carries a pairof sleeve bearings 56 and 57 from which a pair of arms 58 and 59 extend.These arms 58 and 59 carry sleeve bearings 60 and 61 at their upperends, which bearings serve as a support for a horizontal shaft 62parallel to shaft 54. The shaft 62 supports the other roller die 39. Itshould be understood that the two roller dies 39 and 40 are positionedon their respective shafts 54 and 62 so that they are directly oppositeeach other. One end of the shaft 62, as is the case with the shaft 54,extends through the sleeve bearing 61 and carries a sprocket 63 on itsextending end.

As best shown in FIGS. 1 and 3, a motor 64 connected to, or supportedfrom, the platform 38 rotates a sprocket 65 connected to its shafts. Achain 66 serves as the driving connection between the motor drivensprocket 65 and the drive sprocket 47. The sprockets 46, of which thereis one on each of the shafts 43 and 44, are connected by a chain 67,thus insuring that both shafts 43 and 44 rotate in the same directionand with the same speed. The sprockets 45, of which there is one on eachof the shafts 43 and 44, drive sprockets 55 and 63 through chains 68 and69. The resultant rotation of the sprockets 55 and 63 in the samedirection will insure that the two roller dies 39 and 40 are rotated inthe same direction and at the same velocity.

It should be understood that the roller dies 39 and 40 are mounted, withrespect to the shafts 43 and 44,

so that they may swing toward and away from each other about the axes ofshafts 43 and 44, with the extent of their movement toward each otherbeing limited to a definite predetermined position. This closestposition of the dies in relation to each other is such that the flatportions of the dies 39 and 40 are close to, but not actually touchingthe tubing T. This precise positioning of the dies, when in theirforming position as illustrated in FIGS. 3 and 5, is controlled byadjusting screws 70, of which there are four. Each screw is adjustablymounted with respect to each of the arms 50, 51, 58 and 59. The ends ofthe screws 70 are adapted to abut the vertically extending portions 41and 42 of the platform 38.

As clearly shown in FIGS. 2 and 3, the screws 70 are received ininternally threaded blocks 71 carried by the arms and a lock nut 72 isprovided to insure that the adjusted position of the screws 70 will notchange once the adjustment is properly made. The arms 50 and 58 arebiased toward each other by a spring 73 and, in a like manner, the arms51 and 59 are biased toward each other.

During the operation of the apparatus for forming pipettes, it isnecessary that the dies 39 and 40 be positioned some distance apart andthat the dies be moved into forni= ing position with respect to thetubing T only after the tubing has been preconditioned by heating.Control of the movement of the roller dies toward and away from eachother is accomplished by the interposition of a pair of cams 74 and 75between the arms 51 and 5-9 and arms 50 and 58 respectively. The twoearns 74 and 75 are connected together by a shaft 76 with both camsoriented with respect to the shaft so that they actuate the arms in alike manner. Rotation of the shaft to effect rotation of the cams incarried out by a crank arm 77 which has one end fixed to the shaft 76and is pivotally connected at its other end to a horizontal piston rod78 which we tends from a fluid motor 79. The motor 79 is mounted on abracket portion 80 which may conveniently be an integral part of theplatform 38.

The above-referred-to conditioning of the tubing prior to forminginvolves heating of that portion of the tubing T which is to be expandedinto the bulb portion of a pi pette. Heating of the tubing isaccomplished by the use of a flame burner 81. The burner 81 has a thin,elongated opening through which the gas and air mixture is fed andburned, with the length of the burner opening being parallel to thetubing so that its coverage will be sufficient to heat the tubing in thearea where the expansion is to be accomplished. Gas for the burner issupplied through a flexible tube 82 and the burner itself is supportedby a horizontal post 83 which in turn is connected to the verticalportion 42 of the platform 38.

Having described the detailed mechanism which comprises the invention,the following description will set forth the sequence of operation ofthe apparatus and the process of the invention.

With the tail stock 14 of the lathe in its retracted position, a lengthof tubing T is placed with its already tapered end into the chuck 17.The tail stock 14 is then moved toward the head stock 13 and the tubingis inserted within the chuck 18 until it is seated in abutting relationto the bushing 33. With the tubing thus positioned, the motor 23 isstarted and the two chucks will rotate the tubing at a predeterminedperipheral speed. The burner 81 is then turned on. At this time the dies39 and 40 are in retracted position as illustrated in FIG. 2. After thetubing has been heated so that the exposed portion thereof has reached aplastic state, the fluid motor 79 is actuated to move the dies 39 and 40into forming position. As the dies move into forming position the burner81 is shut oif. It should be understood that the motor 64 iscontinuously running and the dies 39 and 40 are continuously rotating ata predetermined velocity so that upon their approach to the tubing Tthey will be rotating in the direction indicated by the arrows on FIGS.2 and 3 and the,

tubing will be rotating in the direction of the arrow 84. With the diesin closed position, as shown in FIGS. 3 and 5, the air is turned on tothe interior of the chuck 18 which permits a controlled air stream toblow against the open end of the tubular blank or tubing T. Pressurewill build up within the tubing T and the softened portion of the tubingwill be expanded outwardly against the concave surface of the rollerdies 39 and 40. From an operating standpoint it should be pointed outthat the dies 39 and 40 do not actually touch the tubing or blank alongtheir straight areas and that the velocity of the dies is such, inrelation to the rotation-a1 velocity of the surface of the tubing blank,that the tubing is rotated at the same velocity as the concave portionsof the dies 39 and 40. After the blowing of air within the tubing iscontinued for a predetermined length of time and the tubing is expanded,the blowing air is cut off and the motor 79 is reversed to move the dies39 and 40 away from each other.

Inasmuch as the dies are always moved into the same position relative tothe tubing T, and the tubing is expanded within the area defined by thecontours of the dies, the bulb or expanded portion of successivelyproduced pipettes will always be the same. In this manner, successivelyproduced pipettes will all be of the same precise dimensions. Thus, thevolumetric calibration of the pipettes may be automatically accomplishedwithout requiring individual calibration, as is the present practice.

Other and further modifications may be resorted to within the spirit andscope of the appended claims.

We claim:

1. A method of forming a pipette from a length of glass tubingcomprising, the steps of supporting the tube at the ends only androtating said length of tubing about its longitudinal axis, applyingheat to a predetermined length of said tubing to render acircumferential portion thereof plastic, moving a pair of opposedconcave members into close proximity to the heated portion of saidtubing, expanding the heated portion against the members by introducingair at a controlled pressure into the tubing, discontinuing theintroduction of air into the pipette after expansion is complete, movingthe concave members apart and removing the formed pipette.

2. Apparatus for forming a pipette from a length of glass tubingcomprising, means for mounting the glass tube only at the ends thereof,means for rotating said length of tubing about its longitudina laxis ina horizontal plane, a pair of concave roller dies, means mounting saidroller dies for rotation about their axes and with their axes parallelto and on opposite sides of the axis of the tubing, means supportingsaid die mounting means for movement toward and away from each other,means connected to said dies for rotating same at the same peripheralvelocity and in the same direction, means connected between said diesupporting means for biasing same toward each other, means positionedbetween said die supporting means for controlling the movement of saiddies toward and away from each other and into close proximity to saidtubing, a motor connected to said means for controlling the movement ofthe dies, means associated with said die mounting means for limitingmovement of said dies toward each other, a heater positioned beneath thetubing for heating the tubing in the area between the roller dies andmeans in engagement with one end of said tubing for introducing fluidinto the interior of said tubing under a controlled pressure to expandsaid heated area into engaging and forming relation with said dies.

3. Apparatus for forming pipettes from lengths of glass tubingcomprising, means for supporting said tube at the ends only and rotatinga length of tubing about its longitudinal axis, a support positionedbeneath and intermediate the length of said rotating tubing, a pair ofconcave roller dies, means for mounting said roller dies with their axeshorizontal and parallel to the axis of the tubing with a die positionedon either side of said tubing,

means for pivotally supporting said mounting means on said support,means connected tosaid dies for rotating same at the same peripheralvelocity and in the same direction, means biasing said die supportingmeans to ward each other, cam means positioned between said die supportmembers for controlling the movement of said dies toward and away fromeach other and into close proximity to said tubing, means associatedwith said die supporting means for limiting movement of said dies towardeach other, a motor mounted on said support and connected to said camfor rotating said cam means, a heater positioned beneath the tubing forheating the tubing in the area between the roller dies and means forblowing air into the interior of said tubing under controlled pressureto expand said heated area into engaging and forming relation with saiddies.

4. Apparatus for forming glass tubing into pipettes comprising, a lathewith rotating chucks for supporting the glass tube only at the endsthereof and rotating a length of tubing, means for driving said chucksat the same speed, a pair of roller dies, a pair of horizontal shaftsfor supporting said dies on opposite sides of the length of tubing withtheir axes parallel to the tubing, pivoted lever means connected to saidshafts for supporting said shafts for swinging movement toward and awayfrom the tubing, means connected to said shafts for rotating said diesat the same peripheral velocity and in the same direction, meansconnected to said pivoted levers for swinging said dies into and out ofclose, equal proximity with the tubing, stop means on said lever meansfor limiting movement of said dies toward each other, means forintroducing air under pressure to the interior of the length of tubingcarried in said lathe and means mounted on said lathe for heating thatportion of the length of the tubing that is located between the dies,said area under pressure expanding the heated portion of the tube intoengaging and forming relation with said dies.

5. Apparatus for forming pipettes from a length of glass tubingcomprising, means for supporting entirely at its ends and rotating alength of tubing about its longitudinal axis, a support plate positionedbeneath and intermediate the length of said rotating tubing, a pair ofconcave roller dies, a pair of horizontal shafts for mounting saidroller dies with their axes parallel to the axis of the tubing, a pairof pivotally supported arms connecting each shaft to said support plate,means connected to said shafts for rotating same at the same peripheralvelocity and in the same direction, means connected between the arms forsupporting said shafts for biasing said pivoted arms toward each other,cam means positioned between said arms for controlling the position ofsaid dies and shafts with respect to each other, means on said pivotedarms for limiting movement of said dies toward each other, a motormounted on said support plate and connected to said cam means forrotating same, a heater positioned beneath the tubing for heat softeningthe tubing in the area between the roller dies and means for blowing airinto the interior of said tubing under controlled pressure to expandsaid heat softened area into engaging and forming relation with saiddies.

6. Apparatus for forming pipettes from a length of glass tubingcomprising, means for supporting at the ends only and rotating a lengthof tubing about its longitudianl axis, a support member positionedbeneath said tubing and intermediate its length, said support memberhaving a pair of spaced apart, upstanding ears, a first pair of arms,means pivotally supporting said first pair of arms on said supportmember at spaced apart intervals, a second pair of arms, means pivotallysupporting said second pair of arms on said support in parallel withsaid first pair of arms, a shaft extending between each pair of arms attheir outer ends, a pair of concave roller dies, means for mounting saidroller dies on said shafts, means connected to said shafts for rotatingsame at the same peripheral velocity and in the same direction, meansbiasing said shafts toward each other, a cam positioned between saidpair of arms for controlling the position of said shafts and dies inrelation to each other, said cams permitting said dies to move intoclose proximity to said tubing, a motor mounted on said support member,means connecting said motor to said cam for rotating saidcam,radjustable means carried by said arms and adapted to engage saidupstanding ears upon movement of said arms to limit movement of saidarms toward each other, a heater positioned beneath the tubing forsoftening the tubing in the area between the roller dies and means forblowing air into the interior of said tubing under control pressure,whereby the tubing is expanded into contact with the accuratelypositioned, rotating, concave dies.

References Cited by the Examiner UNITED STATES PATENTS 1,914,205 6/1933Hooper et al. 65109 X 2,393,979 2/1946 Everett 65-277 3,171,730 3/1965Zauner 65l09 10 DONALL H. SYLVESTER, Primary Examiner.

S. LEON BASHORE, A. D. KELLOGG,

Assistant Examiners.

1. A METHOD OF FORMING A PIPETTE FROM A LENGTH OF GLASS TUBINGCOMPRISING, THE STEPS OF SUPPORTING THE TUBE AT THE ENDS ONLY ANDROTATING SAID LENGTH OF TUBING ABOUT ITS LONGITUDINAL AXIS, APPLYINGHEAT TO A PREDETERMINED LENGTH OF SAID TUBING TO RENDER ACIRCUMFERENTIAL PORTION THEREOF PLASTIC, MOVING A PAIR OF OPPOSEDCONVACE MEMBERS INTO CLOSE PROXIMITY TO THE HEATED PORTION OF SAIDTUBING, EXPANDING THE HEATED PORTION AGAINST THE MEMBERS BY INTRODUCINGAIR AT A CONTROLLED PRESSURE INTO THE TUBING, DISCONTINUING THEINTRODUCTION OF AIR INTO THE PIPETTE AFTER EXPANSION IS COMPLETE, MOVINGTHE CONCAVE MEMBERS APART AND REMOVING THE FORMED PIPETTE.
 2. APPARATUSFOR FORMING A PIPETTE FROM A LENGTH OF GLASS TUBING COMPRISING, MEANSFOR MOUNTING THE GLASS TUBE ONLY AT THE ENDS THEREOF, MEANS FOR ROTATINGSAID LENGTH OF TUBING ABOUT ITS LONGITUDINA LAXIS IN A HORIZONTAL PLANE,A PAIR OF CONCAVE ROLLER DIES, MEANS MOUNTING SAID ROLLER DIES FORROTATION ABOUT THEIR AXES AND WITH THEIR AXES PARALLEL TO AND ONOPPOSITE SIDES OF THE AXIS OF THE TUBING, MEANS SUPPORTING SAID DIEMOUNTING MEANS FOR MOVEMENT TOWARD AND AWAY FROM EACH OTHER, MEANSCONNECTED TO SAID DIES FOR ROTATING SAME AT THE SAME PERIPHERAL VELOCITYAND IN THE SAME DIRECTION, MEANS CONNECTED BETWEEN SAID DIE SUPPORTINGMEANS FOR BIASING SAME TOWARD EACH OTHER, MEANS POSITIONED BETWEEN SAIDDIE SUPPORTING MEANS FOR CONTROLLING THE MOVEMENT OF SAID DIES TOWARDAND AWAY FROM EACH OTHER AND INT O CLOSE PROXIMITY TO SAID TUBING, AMOTOR CONNECTED TO SAID MEANS FOR CONTROLLING THE MOVEMENT OF HE DIESMEANS ASSOCIATED WITH SAID DIE MOUNTING MEANS FOR LIMITNG MOVEMENT OFSAID DIES TOWARD EACH OTHER, A HEATER POSITIONED BENEATH THE TUBING FORHEATING THE TUBING IN THE AREA BETWEEN THE ROLLER DIES AND MEANS INENGAGEMENT WITH ONE END OF SAID TUBING FOR INTRODUCING FLUID INTO THEINTERIOR OF SAID TUBING UNDER A CONTROLLED PRESSURE TO EXPAND SAIDHEATED AREA INTO ENGAGING AND FORMING RELATION WITH SAID DIES.